Method of and apparatus for laboratory investigation of the rolling of ships



Aug. 17, 1954 GRAVROGKAS 2,686,375

METHOD OF AND APPARATUS FOR LABORATORY INVESTIGATION OF THE ROLLING OF SHIPS Filed July 16, 1952 4 Sheets-Sheet l INVENTOR.

Juuus GRPNROGKAS g k W I4 O ATTQRNEYS.

J. GRAVROGKAS METHOD OF AND APPARATUS FOR LABORATORY INVESTIGATION OF THE ROLLING OF SHIPS Aug. 17, 1954 4 Sheets-Sheet 2 Filed July 16, 1952 INVENTOR. Juuus GRWRQGKAS v BY ATTORNEYS.

FIG.2.

J. GRAVROGKAS METHOD OF AND APPARATUS FOR LABORATORY INVESTIGATION OF THE ROLLING OF SHIPS Aug. 17, 1954 4 Sheets-Sheet :s

Filed July 16, 1952 INVENTOR. Juuus GRAVROGKAS' w k m ATTORNEYS FIG. 3.

Aug. 17, 1954 J. GRAVROGKAS 2,686,375

METHOD OF AND APPARATUS FOR LABORATORY INVESTIGATION OF THE ROLLING OF SHIPS Filed July 16, 1952 4 Sheets-Sheet 4 IN V EN TOR.

Juuus Gem/enema. Mk m AT TO RN EYS lvarious parts of theapparatusy Patented Aug. 17, 1954 METHOD OF AND APPARATUS FOR LABORA- TORY INVESTIGATION OF THE ROLLING OF SHIPS Julius Gravrogkas, Cleveland, Ohio 7 Application July 16, 1952, Serial No. 299,181 Claims. (Cl. 35-19) This invention relates generally to a. method of and apparatus for determining or investigating the rolling of ships.

In the stabilizing of ships by means of gyroscopes, it is important to know exactly how the proposed means of stabilizing will affect the ship as soon as it is tossed about by theocean waves.

It has heretofore been necessary, for the purpose of such determinations, to take the ship to sea. This method is, however, inconvenient and disadvantageous in many respects, including the following:

(a) It is extremely expensive.

(2)) Since the ocean Waves cannot be varied as desired, they must be considered or taken as of the time the investigation is being conducted.

(c) The results achieved by such an expensive method are valid only for those ships for which the proportions between the mechanical quantities defining the tossing or rolling are the same as those of the ship under investigation.

(d) It doesnt allow a general decision to be made because to make a general and final decision about gyroscopical stability of ships it is necessary to have a. possibility to change the mentioned proportions within suificiently wide limits as Well as the rolling moment which affects the ship.

The present invention has as its primary object a method of and. apparatus for determining or defining of the resistance of any stabilized ship when affected by waves of various frequencies, "and which method and apparatusovercomes all the aforesaid disadvantages ofpnlor'methods.

My invention comprises an apparatus and method for laboratory investigation which enable the following things to be accomplished:

1. The representation by means of movable parts, of the rolling motion of any shipwhich is stabilized by means of gyroscopes.

2. The provoking oithe rolling moment which should correspond to'any strength of the waves.

3. The selection, in amost efiective Way, of stabilizing equipment 'or parts necessary to stabilize a ship subjected to tossing about bywaves.

;following description, taken in connection with.

the accompanying drawings, in which like numerals designate like parts throughout, and in which Fig. 1 is a side elevational view of'one side of the apparatus embodying the invention;

Fig. 2 is a side elevational view of the opposite side of the apparatus;

Fig. 3 is a View, partly in end elevation, and

Fig. 4 is a transverse cross-sectional view, taken on the line AB of Fig. 3, and

Pig. 5 is an elevational detail of certain related parts of the apparatus whereby motion of rotation is converted into reciprocating motion.

'itererring more particularly to the drawings, the apparatus will be seen to comp-rise a pendulum ill to which a shalt ii, journalled at itsflends in standards l2 and of a frame I4, is rigidly secured. The standards, which are channelshaped in section, are spaced apart and their lower ends extend between and are secured to spaced channel-shaped base members it and it as by means of bolts or the like and by means of pairsof gussets ii and it. A bolt is carrying a. sleeve to secures the lower ends of the standards together.

'l'ile pendulum l9 embodies spaced channelshaped members 2| and 22, the upper and lower ends or which are connected by similar channelsnaped transverse members welded to the members 2i and 22. The plates 23 and 2 5, which are secured to the aligned hanges 2'5 and 26 and to the aligned flanges Z1: and 2c of the members 2| and 21, carry the shaf t H.

'rnreaded round bars 29 and 3d are located on one side or and parallel to the members 2i and.

bolted, respective y, to the nanges 2t and H, and angle members to and at bolted to the clips.

'lne upper ends of the bars 29 and 31 are threaded and .extend'through openings in the 4 angle members to which they are secured by nuts 5: and is threaded upon tne ends or the bars. I118 oars Z9 and 3i are similarly secured at their :lOWGIjends in spaced relationship to themeniber in by means or zshaped clips and 4d angle members ti and i2 into which the bars extend. l'he bars 3i! and 32 are similarly secured to the channel-shaped member '22 or: the

penduium. r

The bars 2d, 3i), 3i" and fit'ca-r'ry internally threaded weights is and-dc, and ie,- and' l8 partly in section, showing the constructionof 1 and t9 and 50, respectively. This permits the A weight to be adjusted along the bars and there- ;by vary the moment ol' inertia or the pendulum so that its height maybe kept within reasonable limits j A motortlis'secur'ed in any desired mariner upon the pendulum it. The shaft 52 of the motorlies parallel to the pendulum and is extended and connected to a worm 53 which is in mesh with a worm'gear 54 fixedly secured upon a shaft 55. A series of gears of progressivelydecreasing diameter are mounted upon'shait 55.

Thegears of this series are adapted to mesh selectively with the corresponding gears of a series 3 of gears 51 of progressively increasing diameter so as to vary the angularvelocity of shaft 58' upon which the gears of the latter serie are mounted.

A disc 59 is fixedly secured upon one end of shaft 58. The disc is formed with a diametrical slot Bl] through which a bolt Bl extends for securement to the disc at various distances from its center. The bolt 6| extends through a slot '62 formed in a slide 63 which is guided in its vertical linear v hereinabove can be utilized to conduct investigations inthe laboratory for the purpose of determining in an economical manner how to gyroscopically stabilize the rolling motion of ships produced by ocean waves of different frequencies. The procedure heretofore employed of investigating the subject ship by actually submitting it to the action of ocean waves was not only prohibitively expensive but the results obtained were movement by a frame 64. The'disc' and bolt ac-' l0 so uncertain as to render impractical the idea of cordingly impart a vertical reciprocatin motion gyroscopically stabilizing the rolling motion of to the slide 63 the extent of which is determined ships. The apparatus described above renders by the distance of the bolt from the center of such investigations economical and translates the th disc, v idea of gyroscopic stabilization of the rolling mo- A sprocket chain 65 is secured to the slide 63 ti n f ps into n exact nd pr tical science. and passes around sprocket wheels 66 and 61. The This apparatus, moreover, can be utilized to teach lower sprocket wheel is rotatably mounted upon y p e action Since q titat ve results can a stub shaft 68 secured to member 22 of the be achieved. pendulum [0. The upper sprocket wheel 61 is Y The pendulum ID of such app preleeted fixedly mounted upon a shaft 69 which is jourupon the differential equations nalled in the members 21 and 22 of the pendulum. dz d The shaft 69 embodies a ring in which the electric f MSW Map0 Sin =0 motor 10 of a gyroscope 'H is firmly held. Separate discs 12 and 13 are mounted upon thershaft d2 1p d W of the motor and constitute selectively variable I +1 ,w-a?+m b+m -d=() flywheels for the gyroscope. V t

The pendulum I9 1 0 C s a y s ope T4 The first differential equation represents the the electric motor 15 of which is firmly held in a equation of the rolling motion of a ship and the ring embodied in a shaft 16 journalled in the second the equation of the oscillatory motion of members 2| and 22 of the pendulum it above a gyroscope together with its frame within the gyroscope H. Separate discs (not shown) simiship. In these equations lar to the discs 12 and 13, can be mounted upon the ends of the shaft of motor i5 and serve the Iy=the momeht P 1ne1"t1a 0f the Ship and e same purpose as discs 12 and gyroscope w1th1n it about the longitudinal axis The shaft 16 carries a disc H which revolves of the Shlpbetween the adjustable poles of an electromagnet I$=the q e of mertla 0f the gyroscope 18 which therefore exerts a braking moment upon gether W ame about the transverse S ,the gyroscope 14 whose function is to stabilize about Whlch the frame rotatesrthe Swing of the Pendulum In place of adjust Z' the moment of inertia of the gyroscope about able poles change in the current of the electro- 40 Its axlsmagnet 13 may be resorted to in order to Vary Ms=the result obtained by multiplying the weight the value of the braking moment. of theship by its metacentric height Th s Themoment of inertia of the gyroscope 14 about resPli 15' referrfld to as the moment of sc the axis of the shaft 16 is made variable by means latlon of the Sh1pof pairs of weightslS and 80 and BI and 82. The Product Of the ght of the gyroscope weights [9 and 80 are adjustably mounted upon a and lts frajme by the distance from he r cenrod 83 suitably secured to the shaft 76. The terof gravlty to the transverse aXiS ut which weights and 32 areadjustably mounted upon a the frame rotates. This is referred to as the rod 84 secured to the shaft l6. Various weights moment of Oscluation of the y pe and its 85 can be secured to the shaft 16 to change the framefrequency of oscillation of gyroscope about the m'zzthe brake moment acting upon the rame 01 haft16 I e eyi p Its magnitude corresponds to A gear 86 is fixed upon shaft ll so as to oscillate mm of angular velocity of the framewith the shaft. Gear 86 is meshed with a rack T1118 mment 1S referred to as the ke numbar 81 slidably received within aguide 88 carried ..by.the standard l2 so that oscillation of the gear axlal angular Velocity of the y ope. 86 produces a vertical reciprocating motion of the 'Y=the of oscillation of the Ocean Waves. rack bar. A similar motion is produced. in a x aihgle 0f inclination of th stylus 89 secured to the rack bar. The stylus Wavesbear upon a paper wrapped around a drum as- =the heehng a of the psembly 99 which rotats'at a o s =the angle of inclination between the axis of the V as to tracea curve upon the paper. An indicator gyroscope and the high axis pdiagram is thus formed the ordinates of which From the twoe uatio n e e, a e s r h l r fle enl 9.? h .tion is derived fro lwm l l tI 1 I I 1: 1 i r r 1 3x: h: l i :g oscillation of the pendulum. my v angle of a ship may b l 1 1 t This equation As heretofore noted the apparatus described is max. PU 1 I I" I! ;'y A [I 7 7 1,1325% g uv. I1! 21 v w y I, *1,

I ing were obtained from the sylvanah An analysis of the immediately foregoing equation shows that the maximum heeling angle of the ship depends upon the following quantities:

l. The ratios 7 I I; and IY.

:' or upon the frequencies of the free oscillation of ,thegyroscope together with its frame and of the ship. 7

2. The ratio 7 that is, upon the braking strength compared'to the moment of inertia of the gyroscope and its frame about the transverse axis about which the frame rotates.

3. Theratio r I I ,I y i I. knownas the swing number, and

4. The frequency ofthe waves aswell as upon the.

maximum angle of inclination of the waves and therefore upon the rolling .moment M s p0 sin 7 which actszupon the ship on the ocean.

- In order that" the apparatus hereinbefore described maybe utilized for the indicated purpose. a

the pendulum 10 is'first calibratedso that its oscillation will be identical'withthe known oscil-- lation of a ship having the greatest frequency of free oscillation of interest. As such a ship I, chose the Sylvana used by Schlick, the famous,

inventor of the" stabilization ofjships by means of gyroscopes, in carrying out his experiments in the expensive and laborio'usmanner heretofore noted. The numerical values hereinafter appear- First, however, it isdesired to set forth certain clarifying observations. The 'expressionMsr i is equal to and is applicableto pendulum ID as well as the ship; When theequationfM =QH a is applied to the pendulum of the apparatus Q equals the Weight of the pendulum and H equals the distanceffromthe center of gravity of the V pendulum to the axis about'whichthe pendulum swings. Correspondingly theexpressions and q) equal the moment of oscillation and theangl of deflection of the pendulum. When the equation Msq =QHip is applied toi-the' ship Q equals the weight of the ship, H the metacentric height, q). the heeli'ng' angle and M theimoment of oscillation; of the ship. Obviously; the'moment Msqi acts uponthe pendulum in" the same way as the analogous moment acts upon the ship.

its lowest position during time t an angle wt and therefore its vertical displacement (r--r cos 'yt) (Fig. 5). Since this is-alsoxthe vertical displacement of the slide 63 through V which bolt 6| extends the velocity: of the slide is 1'7 sin mi.

The motion of the slide is transmitted to the sprocket wheels 66 and 67 by means of the chain fastened to the slide. 7 The peripheral velocity of the sprocket wheels is therefore 1 sin '72? and theirangular velocity where I equals the moment of inertia of the gyroscope about its axis and 012 its angular velocity about its axis. The moment i acts upon the pendulum and realizes the rolling moment Magoo sinfit which corresponds to the analogous rolling moment which acts upon the V shipron the ocean so that r v i There is another moment which also acts upon the ship from without. "Thisis the rolling moment M s o sin t. M5 in this expression equals'the oscillation momentv of--the. ship An .analogous moment must be applied to the pendulum. If theexpression MSQDO sin ytis applied to the pendulum M, equals the oscillation moment of the.

pendulum. The rolling moment M w sin 'yt which mu I t act on the'pendulum' is .i ealizedin such a fContinuing these observationsfand referring to the described apparatus it will be shown below thatthe angular'velocity y of th shaft 58 arg sponds to the frequency of the ocean waves. The

disc 59, which is fastenedduponshaft 58,'ac-

cordingly rotates with an, angular velocity y as does'the boltjfil. When the boltisplaced at a ,wherein Isis the nioment of inertia of.- the distance 1'ifr'om the center of the disc and rotates with an angular velocity it describesfroin,

' Inthe foregoing equation theangular-velocity of i the shaft '58 corresponds to the. frequency of the ocean waves, therelation i r i correspondsto the greatest angle-of inclination hf the ocean waves and the product Iwz'y to the mo ment of oscillation of the pendulum. Since the distance r of the bolt 61 from the center of the disc 59 as well as the axial moment of inertia I of the gyroscope I! can be-varied the relation V 12. canbe made equal tojthe greatest angle qm'Of inclination of the ocean waves and the product Iwz'y to the moment Ms of oscillation of the pendulum;

"To I obtain the stabilizing mo'i'nent which must act on thependulum and correspond to the analogous moment which acts on the ship the gyroscope I4 is mounted upon the pendulum. This l gyroscope functions to stabilize the swing of the pend um- J Turning again to the calibration oftheappara tus so that the; oscillation; oflthe, pendulum; willagree with the rolling motion of the ship Sylvana.v consideration is had of the ratios hereinabove' le ab u "it il ns u aia s o th ment of inertia of the pendulum about its ;axis

equals H, and Ms is the moment of oscillation of the ship or the pendulum. The moment of inertia of the pendulum consists of two parts, namely, the moment of inertia of the weights 43 to 50, inclusive, or I and the moment of inertia of the pendulum and the members fastened to it, or I"y. The moment of inertia, I'y, can be varied within limits by varying the position of the weights; the moment of inertia 1"2 is constant. The pendulum is so designed thatwhen the weights; are placed at the maximum distance from shaft II the ratio 2% I of the pendulum is equal to the analogous ratio of the ship Sylvana, namely Also Iy=I'gIy=204+20=224 kgm. secP and Ms=119 kgm. Therefore,

The swing number of the pendulum is next considered. In this expression, Ix which is the moment of inertia of the gyroscope 14 about transverse axis 16 consists of two parts, variable I): and constant I"x. Th value of IX depends upon the location of the movable weights 19 to 82, inclusive, while the value of 1"x depends upon the gyroscope 14 and the members connected with it and with the shaft H5. When the weights 19 to 82, inclusive, are placed as shown the magnitude of I $=0.18 kgm. sec The value of I i 'x=0.009 kgm. sec. Therefore, Ix which equals ,'-'mI":r1lS equal to 0.189 kgm. sec. The swing number of the Sylvana was twenty times as large as the square of its frequency of oscillation. To obtain correspondence between the pendulum and the ship Sylvana the angular velocity u of the gyroscope 14 about its axis must be calculated from theequation I w M, 27 I.

Since the values of Ix, Iy, w and the frequency of oscillation,

yu- I u are known a value of w can be obtain ed." The,

swing number of the pendulum then becomes equal to the swing number of the ship Sylvana. The next ratio to be considered is r to the frequency of oscillation-of the ship it-' self a This equation takes into account the gyroscope, its ring, transverse shaft, the members fastened to it and the shown position of the weights l9 to'82, inclusive. The value of ms as well as the above shown value of Ix satisfy the noted equation.

-As to the ratio 1,,1, 1, 1,1,, 7 as well as by the rolling moment Msqoo sin 'yt. Therefore, if the noted ratios referred to the pendulum are equal to the same ratios referred to the Sylvana, the oscillation of the pendulum reproduces the rolling of the Sylvana and permits investigation of the rolling of the 'Sylvana when it is influenced by various ocean Waves. Thus, the pendulum'can be used to reproduce the rolling motion of the Sylvana when the frequency of the ocean waves is 'y' and the greatest angle of inclination of such waves is o. The bolt 61 is moved along the slot in the disc. 59 a distance r .so that the ratio Then using the series of gears 56 and 51 I can cause the shaft 58 to rotatewithangular velocity 7, Finally, the necessary weights are added to the shaft of motor 10 in order to equate the product My to themoment of oscillation Ms of the pendulum. It follows that the swinging amplitude of pendulum will be equal to 900 max. which is the rolling amplitude of the Sylvana when it is acted'upon by ocean waves having a frequency and the greatest angle of inclination we. 1

a The apparatus can be used to reproduce the rolling motion of, ships having a. frequency of oscillation which is less than that of the Sylvana.

To demonstrate'this it is first necessary to in-' vestigate the reproduction by the pendulum of the reduced rolling phenomenon of the known ship Sylvana. It may be assumed, accordingly, that the ocean wave oscillation is accelerated n times and that the waves are correspondingly reduced without changing their shape. While the frequencyof oscillation of the actual ocean waves is v yielding aperiod of oscillation of the assumed frequency and period of oscillation become 71 and respectively, where 71:11. ,On the other hand, I imagine that the corresponding mechanical magnitudes, upon which the rolling motion of the ship gSylvan depends, are] so changed that the maximum heelingfangle is retained. Itcan be obtainedif the values of theratios a and Mi M'.-- M1. 7

can be retained;

From the foregoing it is-concluded that if the period of oscillation of the ocean waves is reduced n times, and if at the same time the moments ofinertia 'Ix and-I -of the Sylvana are reduced 11 times and :the moment of inertia of the gyroscope stabilizer Iz and the brake. number mzare respectively reduced it timesthe maximum heeling angle of the Sylvanawouldbe-unchanged.

This conclusion has equal validityfor 'every ship.. Itis also valid for the pendulum of the described apparatus because the Equations 1, 2, 3 and 4 expressedabove are-applicable as well to the pendulum. Of course we canonlyimagine the i 7 above mentioned change-of oscillation ofthesea waves as well asthe corresponding changes in Ix, Iy, I2 and 1m of the ship Sylvana. But all considered changes can'berealized-on the. pendulum and in this-way can be obtained the maxi.-. mum heeling angle of the Sylvana by means of the reduced rolling phenomenon. i

Assume that the ship Sylvana is afiected by sea waves of a frequency-of oscillation of 'y' and greatest angle of inclination of zpo. To reproduce by the pendulum the maximum heeling angle of the Sylvana obtained by the n times reduced rolling phenomenon it is necessary to realizethe angular velocity of the shaft 58 of m a reduction of the values of IX andl by n times and a reduction of the values of 12 and 1112 by n times. Since we assume that the shape of the ocean waves and therefore the greatest angle of their inclination, p, remain unchanged it is concluded that the amplitudeMs u', of the rolling moment is unchanged because the moment of oscillation Ms of the pendulum remains constant. Since Megan is unchanged the value of the expression Iw T'Y IL 7 must remain unchanged since 'Iw' 'n I M aP'O R But the ratio equals the greatest angle of inclination of the waves and is therefore unchanged. Consequently the product Iwz'y'n is unchanged; since in the foregoing example the frequency of oscillation, of the ocean waves has been increased.

10 n times the moment of inertia'of the gyroscope H must be reduced 12 times so that These changes can readily be realized by the described apparatus. The angular velocity of the shaft 58 can be increased n times so that it equals 1w by means of the series of gears 56 and 51. The movable weights 43 to 50, inclusive, and the movable weights 19 to 82, inclusive, serve to reduce the moment of inertia, 1y, of the pendulum about its axis of swing and the moment of inertia, Ix, of the gyroscope 14, its ring and all members connected with, it about its transverse axis 16 by n times.

' inertia L; by Hi times we can remove the corresponding number of discs from rods 83 and 84. The apparatus is so designed that when ;'the weights 43 to 50, inclusive, are moved as close as possible to the axisof swing of the pendulum, the moment of inertia Iy i reduced by 10 times. Thus, if we'want'to use Vlfltimes reduced rolling phenomenon to reproduce the biggest angle of heel of the Sylvanawhen it is affected by ocean waves having a frequency of oscillation of 'y',we must, in addition to' the movement of the noted weights as set forth, increase the angular velocity of the shaft 58 by /10. Finally the moments of inertia Iz and I as Welljts the brake number, mz, must be reduced by 10 times, which is done by putting thenecessary weights or flywheels to the shafts of-the motors '10 and 15, and by moving the poles of the electromagnet 18 or by changing the current in the electromagnet. V

When all this has been accomplished the swing of the pendulum reproduces the maximum heeling angle of the Sylvana when it is affected by ocean waveshaving a frequency of oscillation of :y and greatest angle of inclination of o. Otherwise, if it is desired to obtain not only the maximum heeling angle of the Sylvana but to investigate by what values of ratios M. 1,, max.

of the pendulum, which is obtained when the weights 43 to 50, inclusive, are at the greatest distance from the axis of swing of the pendulum. As to the effect upon the size of the pendulum it is not desirable to increase the length of the rods on which weights 43 toil), inclusive,-and 19 to 82, inclusive, are mounted or the size of the weights. We can consider, however, that the rods are lengthened and the 'weights moved away from To reduce the moment of a I, max.

and in the frequency of oscillation of the gyroscope",

m. I I max.

K times so as to make them equal to the values of the ship under consideration. braically, these equations become Also the swing number and the ratio Stated algeand . 1 define the swing of the pendulum as well as the rolling motion of the considered ship. Since Iy max. and Ix max. are considered as being increased K times, the swing number of the pendulum,

I max. I, max.

I I max. K I max. K that is, the swing number is reduced K times. Since the swing number of the pendulum and of the considered ship, represented as N, are equal the equation I '22., K I,, max. I, max. is obtained. This is accomplished by adding the necessary weights axially to the gyroscope 14 so that the moment of inertia Iz becomes I'z. Then 1 K 1 max. I max.

and

2 I',= Z NI max. I, max.

Also, the ratio mg I max.

is reduced K times since the moment of inertia Ix max. of the gyroscope about the transverse axis is increased K3 times. Since the ratio I max.

Thus to cause the pendulum to represent the M, m, and I:

cannot be obtained the method of reduced rolling phenomenon is employed to reproduce a maximum angle of deflection of the pendulum equal to the maximum heeling angle of the ship under consideration. As mentioned above the frequency of oscillation of the ship is K times smaller than the minimum frequency of oscillation,

I max.

of the pendulum. Employing the method of reduced rolling phenomenon the frequency of wave oscillation, 'y is considered increased K times and the shape of the waves unchanged so that the greatest angle of inclination, 900 of the waves remains the same.

Using the K times reduced rolling phenomenon, the moment of inertia of the pendulum about its axis of swing, which in the example set forth equals Iy max. K is reduced K times so that it becomes equal to Iy max. This can be realized by placing the weights 43 to 50, inclusive, at the extreme positions shown. Similarly the moment of inertia of the gyroscope 14 about its transverse axis, Ix max. K is reduced K times and becomes Ix max. This is obtained by positioning the weights 19 to 82, inclusive, as shown. The magnitudes of the brake number and the moment of inertia of the gyroscope 14 about its own axis must also be reduced and by an amount equal to K times. The brake number QK Ix max. then becomes QKIX max., and the moment of inertia of the gyroscope 14 2 NI, max. I, max.

becomes EJNI, max. I, max.

The first change is obtained by movement of the poles of the electromagnet or by changing the current in the electromagnet. The second change is obtained by adding the necessary weights axially to the gyroscope.

To summarize the maximum heeling angle of any ship that is stabilized by gyroscope and the frequency of oscillation of which is K times smaller than the frequency of oscillation of the ship upon which is based the construction of laboratory apparatus, can be reproduced in the following manner:

1. The weights 43 to 50, inclusive, are placed as far from the axis of swing of the pendulum as possible.

2. The weights 19 to 82, inclusive, are placed as shown.

scope 14. so that. its moment-of inertia about: its, own. axis. equals g /NI}, marl, max;

where N. equals the swing numberof the ship under consideration.

4; Bythe' use of "the movable-poles ofthe electro= magnet 18: or by the current: in: the electromagnet make the brake number equal to QKIi: max where Q equals:

the ratio r/R equals the greatest angle. of

inclination, of" the waves.

7-. The necessary Weights are. added to the gyro scope 1 I to-make'its moment'of'inertia, I, about its own axis equal" to.

Itis tdbe. understood thatthe'form. of my in vention, herewith shown and described, isrtosbe. taken as a. preferred example of. the same, and that various changes in the shape, size. and. a1:- rangement. of parts. may be; resorted. to,- without departing from: the-spirit of. myinvention; or the. scope of the subjoined claims.

I- claim:

1. Apparatusfordetermining; in the laboratory,- the: stabilizers required. to stabilize the rolling, motion: of ships-effected by. Waves havingdiffer-- ent. frequencies of oscillatiom comprising asup.- port, a. pendulum-,. a shaft swingably' mounting, said pendulum on said; support, means. for. oscillating said pendulum, and means. on said pendulum for stabilizing the oscillation of. said pendulum, said last-named means embodying. a gyro.- scope.

2. The apparatus of claiml in which the gyroscope. carriesmeans for varying-themoment of inertia of the gyroscope-about its-transverse axis.

3. Apparatus for determining in the laboratory. the stabilizers required to stabilize the. rolling motion of ships" effected" by waves having different frequencies of oscillationv comprising a support; a pendulum, a shaft swingably mounting said pendulum on said. support, a shaft journalled onsaid pendulum, means on said pendulum for rotating said latter shaft, means on said pendulum for converting the rotation of said latter shaft into a rectilinear reciprocating motion, a gyroscope having a shaft journalled on said pendulum, means operatively connecting said lastmentioned means with said gyroscope shaft for imparting oscillating motion to said gyroscope about the axis of its said shaft, and a stabilizing gyroscope having a shaft journalled on said pendulum.

4. The apparatus of claim 3 in which the means for rotating said second-mentioned shaft includes means for varying the angular velocity thereof.

5. The apparatus of claim 3 in which the means for converting the rotation of said second- Mi. mentioned? shaft:- intmrectilinear: reciprocating motioniisavariable,

Apparatus for, determming; in; the. labora tom; the stabilizers, required; to; stabilize the rollingmoticnof shipseffected by waves. hayinggdif ferent frequencies ofv oscillation; cpmprising: a support, a. pendulum. a. shaft swingably mounts me; said: pendulum on:2 said: support; means.= for oscillating said penduluim. and: means: including a gyroscope' for stabilizing the-swing. of pen dulum, saidr latter,v means also including; means fon'exerting a brakingmoment onsaid gyroscope inaitsi-swinging; about; its; transverse; axis;

7: Apparatus zforrdetermining' the laboratorse' the stabilizers-r requiredi to: stabilize the rollin mdtionioffi ships-3 effected: bywaveshaving. different frequenciesof: oscillation comprising a. support; apendulum, a shaft, swingably mounting said pendulum onsaid support, meansfor-oscillating said pendulum; andv means. on said pendulum: for stabilizing the oscillation of? said pendulunr. said latter means; embodyinga gyroscope; having: a. transverse shaft, journalled'- in: said: pendulum: at a. right angle to, said shaft of: said. pendulum, a: disc: secured toone end: of said; transverse shaft, and: an electromagnet having" adjustable. poles; said" disc; lying between. said. poles.

8;. Apparatusfor determining. in the; laboratory. the stabilizers required. to stabilize the rolling. motion ofv ships; effected by" waves.- having: differ-- ent frequencies: of: oscillation comprising: a: sup.- port; a pendulum; ashaft swingably' mounting; saidpendulum. on. said support; means. including. a. gyroscope for; oscillating said, pendulum, and means on said pendulum including-a2 gyroscopefor' stabilizing the. oscillation of said: pendulum, a" gea mounted 1112011188311 shaft; and: oscillating withzsaid: pendulum; a. guide secured. to said:- sup, port, .a rack bar slidably mounted on said? guide andtmeshingrwith; said gear; a. stylus secured to. said: rack: bar,. and-1a. drum journalled on..said.f'sup. port, said: stylus: cooperating. with saidi drum the. production. of indicator: diagrams.

9;. Apparatus.- of the: character described comrisingt a. suppcrt,.alpendulum-,.a= shaft swingably;

; shaft, connecting said: first-mentioned; means with: said transverse shaft for effecting; oscillae tion. of 'saidgyroscope aboutsaid; transverseshaft, and a stabilizing gyroscope having a transverse shaft journalled. on said. pendulum.

10; Apparatus of the character described comprising a support, a pendulum, a shaft swingably mounting said pendulum on said support, a motor mounted on said pendulum, a shaft journalled on said pendulum, variable speed mechanism operatively connecting said motor with said latter shaft, variable means on said pendulum for converting the rotation of said latter shaft into vertical reciprocating motion, a gyroscope having a transverse shaft journalled on said pendulum, means including a member mounted on said transverse shaft connecting said first-mentioned means with said transverse shaft for effecting oscillation of said gyroscope about said transverse shaft, and a stabilizing gyroscope having a transverse shaft journalled on said pendulum.

11. Apparatus of the character described comprising a support, a pendulum, a shaft swingably mounting said pendulum on said support, a motor mounted on said pendulum, a shaft journalled on said pendulum, variable speed mechanism operatively connecting said motor with said latter shaft, a slide mounted on said pendulum, means connecting said latter shaft with said slide and converting the rotation of said latter shaft into reciprocating rectilinear motion of said slide, a gyroscope having a transverse shaft journalled on said pendulum, means connected with said slide and a member mounted on said transverse shaft for converting the reciprocating motion of said slide into oscillating motion of said gyroscope, and a stabilizing gyroscope having a transverse shaft journalled on said pendulum.

12. Apparatus of the character described comprising a support, a pendulum, a shaft swingably mounting said pendulum on said support, means associated with said pendulum for varying its moment of inertia about the axis of said shaft, a motor mounted on said pendulum, a shaft journalled on said pendulum, variable speed mechanism operatively connecting said motor with said latter shaft, variable means on said pendulum for converting the rotation of said latter shaft into vertical reciprocating motion, a gyroscope having a transverse shaft journalled on said pendulum, means including a member mounted on said transverse shaft connecting said variable means With said transverse shaft for effecting oscillation of said gyroscope, and a stabilizing gyroscope having a transverse shaft journalled on said pendulum.

13. Apparatus of the character described comprising a support, a pendulum, a shaft swingably mounting said pendulum on said support, means associated with said pendulum for varying its-- moment of inertia about the axis of said shaft, a motor mounted on said pendulum, a shaft journalled on said pendulum, variable speed mechanism operatively connecting said motor with said latter shaft, variable means on said pendulum for converting the rotation of said latter shaft into vertical reciprocating motion, a gyroscope having a transverse shaft journalled on said pendulum, means including a member mounted on said transverse shaft connecting said first mentioned means with said transverse shaft for effecting oscillation of said gyroscope, a stabilizing gyroscope having a transverse shaft journalled on said pendulum, means associated with said stabilizing gyroscope to vary its moment of inertia about the axis of its transverse shaft, and means associated with said stabilizing gyroscope to vary its moment of inertia about its own axis.

14. Apparatus of the character described comprising a support, a pendulum, a shaft swingably mounting said pendulum on said support, means associated with said pendulum for varying its moment of inertia about the axis of said shaft, a motor mounted on said pendulum, a shaft journalled on said pendulum, variable speed mechanism operatively connecting said motor with said latter shaft, variable means on said pendulum for converting the rotation of said latter shaft into vertical reciprocating motion, a gyroscope having a transverse shaft journalled on said pendulum, means associated with said gyroscope for varying its moment of inertia about its own axis, means including a member mounted on said transverse shaft connecting said first mentioned means with said transverse shaft for effecting oscillation of said gyroscope, a stabilizing gyroscope having a transverse shaft journalled on said pendulum, means associated with said stabilizing gyroscope to vary its moment of inertia about the axis of its transverse shaft, and means associated with said stabilizing gyroscope to vary its moment of inertia about its own axis.

15. Apparatus of the character described comprising a support, a pendulum, a shaft swingablymounting said pendulum on said support, means associated with said pendulum for varying its moment of inertia about the axis of said shaft, a motor mounted on said pendulum, a shaft journalled on said pendulum, variable speed mechanism operatively connecting said motor with said latter shaft, variable means on said pendulum for converting the rotation of said latter shaft into vertical reciprocating motion, a gyro scope having a transverse shaft journalled on said pendulum, means associated with said gyroscope for varying its moment of inertia about its own axis, means including a member mounted on said transverse shaft connecting said first mentioned means with said transverse shaft for effecting oscillation of said gyroscope, a stabiliz- References Cited in theme of this patent UNITED STATES PATENTS Number Name Date 1,925,138 Dillman Sept. 5, 1933 1,987,763 Tea Jan. 15, 1935 2,024,621 Barker Dec. 1'7, 1935 2,255,899 Ross Sept. 16, 1941 2,396,617 Von Den Steinen Mar. 12, 1946 2,441,556 Bolster May 18, 1948 

